F Hadavi: Nannofossils from the Konarak area, Iran... , p. 195-197.

Journal of Nannoplankton Research, 22, 3, 2000.

CALCAREOUS NANNOFOSSILS FROM THE KONARAK AREA OF
THE COASTAL MAKRAN, IRAN: A NOTE
Fatemah Hadavi
Dept. of Geology, Faculty ofScience, Ferdowsi University ofMashhad, Iran

Abstract: For the first time, the calcareous nannofossils from the marly deposits of Konarak (Iraniancoastal Makran) have been studied using both light- and electron-microscopy. From the nannofossil data,
the material has been dated as NN11 (Late Miocene Discoaster quinqueramus Zone) of Martini's (1971)
standard biozo nati on scheme.

Introduction
The Konarak area is located in the eastern part of the Iraniancoastal Makran (S oflatitude 26°N). The regional geologyof the Makran of Iran has been studied by an Australiangroup (McCall et al., 1985; McCall, 1997) for the Geological
Survey oflran (GSI), whilst the Makran ofPakistan, a direct
geological continuation of the Iranian Makran, has beenstudied by Platt et al. (1985), with nannofossil data outlinedin Harms et al. (1984). TheMakran is thus known to be of
considerable tectonic interest, and has significant
petroleum potential.
In 1989, a group of geologists from the GSI studied theIranian Makran region (part oftheMakran Project, for which> 100 nannofossil samples were analysed by the author).
The aim of the present work is to provide a date for selected
Neogene sedimentary deposits of Konarak using
nannofossils . The studied samples and photographic
negatives are deposited in the Geological Unit of theFerdowsi University ofMashhad.

folded. A total of 16 samples were collected for the studyof nannofossils and ostracods. The samples arecharacterised by a high percentage of ostracods and lackofforaminifera (except in one sample).

Biostratigraphy
All of the samples except for KM5, KM6, KMll andKM15
were barren. Preservation is generally poor to moderate,with evidence of solution and overgrowth on specimens.
The abundance of calcareous nannoplankton in thismaterial is low but a few samples contain enough index
fossils to date them. Coccolith species recognised in thisstudy are listed in Table 1 along with their relative
abundances (full taxonomic references can be found inPerch-Nielsen, 1985).
Discoaster brouweri forms 50% of the Discoasterassemblages in the productive samples and was foundtogether with rare Dis coaster quinqueramus andAmaurolithus ninae. On the basis of the first occurrencew...JQ.

11)..-TAXON(/)
Calcidiscus macintyrei
Coccolithus pelagicus
Reticulofenestra pseudoumbilicus
Reticulofenestra haqii
Reticulofenestra minuta
Rhabdosphaera clavigera
Pontosphaera indooceanica
Amaurolithus sp.
Amaurolithus ninae
Sphenolithus abies
Helicosphaera carteri
Helicosphaera cf . H. sellii
Discoaster brouweri
Discoaster neorectus
Oiscoaster ca/caris
Oiscoaster variabi/isDiscoaster quinqueramusThoracosphaera sp.
NANNOFOSSIL ZONE~~~RRRRF RRRFFFFF FF FFcVR
R::::! ..- .... CO<( ::::! ::::! ::::!

F igure 1: Locati on ma p of the stu died area.

Methods
Smear-slides were prepared from raw samples for LManalysis. These were studied with the LM at x1250
magnification. SEM examination was carried out on just
one sample. The main purpose of this examination was toillustrate the key species used in the age determination.
Section studiedA location map and cross-section for the interval studied
are shown in Figures 1 and 2, respectively. The section is800m thick, composed of soft, greenish-grey mar! with fineto medium-grained sandstone intercalations, and is strongly11)::::!
~F c F VR
F F c Fc F c cc c c cccc Fc F F VRc c
NN11Table 1: Distributi on of Late Miocene calcareous nan.nofossils,Konarak area. VR = very rare (1 %), R = rare (<4%), F = few (4-8%),
C = common (8-12%).

195

F Hadavi: Nannofossils from the Konarak area, Iran. .. , p. 195-197.

Journal of Nannoplankton Research , 22, 3, 2000.

sN
angular

KM16

marts with
fine-/medium-grainedintercalations

KM9

KM1

Figure 2: Schematic geological section of the marine deposits of the Konarak area.

of A. ninae in NN11 and the presence of D. quinqueramus,
the sampled interval falls within NN11 (D. quinqueramus
Zone) ofMartini's (1971) standard zonation.
The presence of abundant shallow-water ostracods
indicates a shallow marine environment for this basin. Thismay have implications for the biostratigraphic
interpretation of the nannofloras, in that the assemblage
may be reworked: Young (pers. comm., 1997) foundreworking to be a pervasive problem in the Makran ofPakistan
Acknowledgement .
Thanks to Dr. J.R. Young for his helpful comments
concerning this manuscript.

References
GSI Geological map oflran (Makran series) 1:100 000. Geological
Survey of Iran, Ministry of Mines & Metals.

Harms, J.C., Cappel, H .N. & Francis, D.C. 1984. The Makran
Coast of Pakistan : its stratigraphy and hydrocarbon
potential. In: B.U. Haq & J.D. Milliman (Eds). Marine
geology and oceanography of the Arabian Sea and coastal
Pakistan. Van Nostrand Reinhold, New York: 1-26.
Martini, E. 1971. Standard Tertiary and Quaternary calcareous
nannoplankton zonation. In: A. Farinacci (Ed.). Proceedings
II Planktonic Conference, Roma, I 970, 2: 739-785.
McCall, G.J.H. et al. (Compiler) 1985. Explanatory text of theTahrui quadrangle map. Geological Survey oflran, Tehran.
McCall, G.J.H. 1997. The geotectonic history of the Makran
and adjacent areas of southern Iran. J. Asian Earth Sci.,
15(6): 517-531.
Perch-Nielsen, K. 1985. Cenozoic calcareous nannofossils. In:
H.M. Bolli , J.B. Saunders & K. Perch-Nielsen (Eds).
Plankton Stratigraphy. Cambridge University Press: 329426.
Platt, J.P., Leggett, J.K., Young, J.R., Raza, H . & Alam, S. 1985 .
Large-scale sediment underplating in the Makran
accretionary prism, southwest Pakistan . Geology, 13: 507511.

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F. Hadavi: Nannofossils from the Konarak area, Iran ..., p. 195-1 97.

Jou rnal of Nannopl ankton Research, 22, 3, 2000.

PLATE 1

D. brouweri
Neg.# 94-FH-8

D. brouweri
Neg.# 94-FH-14

D. brouweriNeg .# 94-FH -15

D. brouweri
Neg.# 94-FH-19

D. brouweri
Neg .# 94-FH -17

D. brouweri
Neg.# 94-FH -21

D. brouweri
Neg .# 94-FH-23

D. brouweri
Neg .# 94-FH-24

D. brouweri
Neg .# 94-FH -27

D. brouweri
Neg.# 94-FH-40

D. brouweri
Neg.# 94-FH -27

Discoaster sp.
Neg.# 94-FH-35

D. brouweri
Neg.# 94-FH -30

D. brouweri
Neg .# 94-FH-31

D. brouweri
Neg .# 94-FH-32

D. calcaris
Neg.# 94-FH -39

D. quinqueramus
Neg.# 94-FH-36

D. quinqueramus
Neg .# 94-FH-37

D. variabilis
Neg.# 94-FH-34

D. variabilis
Neg.# 94-FH-33

A. amplificus
Neg.# 94-FH-28

Amaurolithus sp.
Neg.# 94-FH-29

H. cf. H. sellii
Neg.# 94-FH-38

Thoracosphaera sp.
Neg.# 94-FH-41

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